Electric discharge device with internal capacitor



May 17,1949. CUMMlNGs 2,470,605

ELECTRIC DISCHARGE DEVICE WITH INTERNAL CAPACITOR Filed Feb. 14, 1947 'III/IIIIIMIIII/I/IM/IIIII% o I Inventor: Harold R. Cummings,

bg MAM His Attorneg.

Patented May 17, 1949 ELECTRIC DISCHARGE DEVICE WITH INTERNAL CAPACITOR Harold R. Cummings, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application February 14, 1947, Serial No. 728,553

4 Claims.

My invention relates to electric discharge devices particularly of the transmitting type.

In the operation of electric discharge devices, it is often desirable that the control grid be shielded from the anode. Also, at higher operating frequencies, it is desirable to connect the screen grid with the cathode through a capacitor to maintain these electrodes at the same high frequency voltage. In accordance with an important aspect of my invention, I provide an improved capacitor construction within an electric discharge device which connects the screen grid and cathode together with respect to high frequency voltages. The improved structure also provides a support for the screen grid and a shield completely shielding the control grid from the anode.

It is an object of my invention to provide a new and improved electric discharge device.

It is another object of my invention to provide a new and improved capacitor construction in combination with the electrodes of an electric discharge device.

It is a still further object of my invention to provide a compact and rugged electric discharge device having a capacitor incorporated within the envelope and connected between the screen grid and cathode of the device.

My invention will be better understood by reference to the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims. In the drawing, Fig. 1 is an elevational view in section of an electric discharge device embodying my invention; Fig. 2 is a sectional view taken along the line 2-2 of Fig. 1; Fig. 3 is a sectional view taken along the line 33 of Fig. l, and Fig. 4 is a. sectional view of the capacitor construction taken along the line 4-4 of Fig. 2.

Referring now to the drawing, I have shown my invention embodied in a transmitting type of electric discharge device including a generally cylindrical glass envelope 1, closed at its lower end by a dish-shaped header 2 through which are sealed a plurality of lead-in conductors 3-! inclusive. As illustrated, each lead-in conductor is bonded to a surrounding sleeve 3, which is sealed at one end to the glass header 2.

The anode 9 of the device is bell-shaped and is supported from the opposite end of the envelope by a supporting stud I connected at one end with the closed end of the anode and bonded at the other end to an inverted cup-shaped terminal II, which is sealed at its lower edge to a flange [2 formed on the envelope wall.

The particular embodiment of my invention illustrated is a tetrode and includes in addition to the anode 9, a screen 01 number two grid l3, a control grid 14, and a double helical filament [5 including a central supporting post It. These elements are supported in concentric and coaxial relation within the anode 9.

The end terminals of the cathode are connected with lead-in conductors 3 and l by conductors I! and I8 of smaller diameter. The center post I6 is supported at its lower end by a circular disk [9 of insulating material which is, in turn, supported on shoulders provided on lead-in conductors 3, 4, and l. The shoulders are provided at the junction of the lead-in conductors 3 and 4 for example, and the shoulder conductors I1 and I8. The center post l6 terminates in a bolt 20, which extends through a central aperture at the disk l9 where it is secured by a nut 2|. The control grid I4 includes a plurality of U-shaped elements which are bonded at their lower ends to a cylindrical sleeve 22. These elements may be secured together at the cross-over points, by welding to a washer or, as illustrated, by means of a hollow rivet 23. The grid assembly thus formed is supported from lead-in conductors 5 and 6 by conductors 24 and 25. The screen grid 13 is of generally similar construction and the individual elements are joined together at their cross-over points by welding to a washer 25. At the lower end the grid elements are bonded to a flanged collar 21 which, in assembly, is joined to a similar collar 28 carried by an apertured shield and supporting member 29. The member 29 is formed of conducting material and is supported from the insulating disk [9 by means of a cylindrical metal member 39 having an inturned flange 30' at its upper end. The lower edge of the member 33 rests on the disk [9 and provides the support for the screen grid assembly. This member also provides one plate of a capacitor assembly which is completed by a second cylindrical shield member 3| connected with the screen grid supporting member 29 and by a third cylindrical member 32. The member 32 is provided with an inwardly directed flange 33 at its lower end which is secured to the disk [9 by rivets 34. An electrical connection between the central post of the cathode and the member 32 is provided by a conducting strap 35 which terminates in a conical terminal 36. The terminal 36 is secured by the nut 21 which secures the central post 16 to the supporting disk l9. The marginal portion of the member 29 and the inwardly directed flanges on the capacitor elements 30 and 3| are bonded together as by welding. As

3 illustrated, member 3| is provided with a circumferential rib 31 which extends upwardly toward the anode of the device, functioning to minimize the escape of the electrons from inter-electrode space. Elements 3| and 32 are maintained in spaced relation by insulating members 38 which are received-in suitablerslots formed incthe: intermediatetcapacitor element 32. =As illustrated, these spacers are slotted on the sides to receive the edges of the member 32 defining the recesses and in this way to determine positivelythespacing between the capacitive elements "30, 3-l, .and 32.

The disk IQ of insulatingzamaterial:;is:':firmly held against the sho11lders 'provided by the leadin conductors 3, 4, and I by means of sleeves 39 bonded to conductors I1 andwlfi lwhiclrtextend from lead-in conductors 3 and 4 and to a conductor 40 which is connected with lead-in conductor l and which extends through the member 29 andiswsecured ztheretorbytausleeve;Al. It 'will be apparent.thatz-leadeinzponductorl provides-an external y accessible: connectiom with the. screen assembly :as welle as casmeans -fori securing the capacitor assembly sztogether. The assembly: is further secured; :by ,a rivet M2 which: :extends through the assen-"rblyzandiis provided with sleeves 43 and M bearing::respectiuelyoon :the insulating disk ll 9 andlthe memherfl.

'. From :the. =ioregoingcuietaile'd description it ;will be apparent. that; myrimtention: provides; an improved a:assemblycavhichzzinoorporates ..a 'bypass capacitor withinrt-her-tuberen el'opez and-between the =screen:;grid= andxcathode. Tilt .is apparent that many of the'struotural ieatnrescmayrhe :employed .ployed regardlesmofithelelectrodes ton-which the capacitor is. connected. #:Atdshersame: time, the structureizprovides:z:aashleldtbetweenixthe :anode and control: grid whichsis-ishaped dzo'sminimize :the escape ref 1 electrons 'stifirom ,lz-the 5.:inter-electrode space. J-ThiSiStIIIGtUI'Etcflmbinslthfi shieldingand capacity;,:.providing: d-nnctionsa and, at: the same time; provideszaexcompactaand: rigidwsupporting structure for. the-- yariouss. elements ;of',-the device. The means for :supportingxthe screen :grid including' theacollars rifle-and; 28;":failita-te lining 411p of the individualvelementsibf .the control and screen grid structures,,duringeassembly. ;iIt:is apparent that .after the :controlrgridisxassembled: :on .;the header-that the: soreenwgrid assembly :.maybe placed:in positionrwitlritheimrtending.:flanges of collars 21;.and: 28 in contacttand .the; screen. grid rotated until :the :individualselementsrare in: line Withuth .elementsslof the control-grid. The flanges are/thenweldedttogether.

While I :have describedand; :illustrated a particular "embodiment-eofi-nny.invention,' it will -2be obvious. 'to those'eski'lledl in-lxthe art: that 1 changes and:modificationsrmaynbermade'without departing. from my invention in itabroader aspects. and I: therefore, aimeinethet appended claims .to cover all such changestarldrmodifications asv fallrwithin the :true spiritandlscope oimyinvention.

What Lclaint;as::nev\tandrdesire-towsecure by Letters. Patenteofi theUmted States-is:

1. electric-dischargedevice;including anenvelope,.--.a; pluralityaof conductorsasealed. through said envelope, a generally planar body of insulating material supported from said conductors, a pair of cylindrical conducting members supported from said insulated member in closely spaced relation and providing the plates of a capacitor, one of said conducting members having aninwardlydirectedzflangeyanda grid supported from saidfiange.

2. An electric discharge device comprising an envelope, a cathode, a control grid, a screen grid,

. and an anode supported within said envelope in concentric relation, a plurality of lead-in conductors sealed through said envelope, an insulatingsupportcarried by said lead-in conductors, a=generally cylindrical conducting member secured to said support and to said screen grid, a

- second cylindrical conducting member connected with said cathode and supported by said insulating support, said second conducting member extending in spaced and insulating relation With respect to said'firstcylindrical member,'- and conducting means extending'z'from-wcertain of said lead-in conductors tosaid control' grid; said conductor means beingshielded :fromsaid: anode by said generally cylindrical conducting member.

3. An electric-discharge:device-comprising an envelope, a cathode, acontrol grid-,a screen grid, and an anode supportedavithin-said envelope in concentric relation azplurality of lead-in con ductors sealed throu h said envelope, an insulating support carried by said :leaddn "conductors, a generally cylindrical.conducting-member secured to. said support and to said-screengrid, a sec- 0nd cylindrical :conductingrmember connected with said cathode andsupportedby: said insulating support,said secondaconducting member extending in spaced and insulatin relation with respect to said first-cylindrical-mem-ber and cooperating therewith to-prov-ideza capacitor.

4. An electrictdischarge device-comprising an envelope,- an anode; a. grid velectrode, and a :filamentary cathode mountedain concentric relation in the order named within said envelope said cathode being of the filamentary itype'and .in- .cluding a pair ofnend-terminalsand a central terminal, va pluralitywof leadein conductors sealed through said envelope: and including :a pair of conductors connected with the, :end terminals of said cathode, an insulating member supported from said pair of :lead-inconductors, a::pair:of conducting members of extended area secured to said insulating member .in; spacedand insulated relation providing a capacitor means connecting the central terminal of;:saidcathode: with I one of said. members and. means supporting x'said grid electrode from the otherptsaid members.

HARQHDR. .GUMMlNGS.

REFERENCES. CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,256,293 Salzberg Sept. 16, 1941 2,356,230 Kentner Aug. 22, 1944 

